How much servo?
Discussion
How much servo do you have? My pedal drops a little but I seem to have to press quite hard to stop. Don't get me wrong, boy does she stop but a discussion on pipes crumbling made me wonder if mine has enough servo.
Is there a better test than pump the pedal and start the engine as mine's always rock solid.
I suspect it's more likely that my E39 is typically over-servo'd though
Is there a better test than pump the pedal and start the engine as mine's always rock solid.
I suspect it's more likely that my E39 is typically over-servo'd though
Difficult to gauge, but I would echo the comments on checking the vacuum hose reasonable regularly as it does perish and given the angle it has to enter the servo, the one way valve sometimes doesn't fit as snugly as it could, it's only a push fit into a rubber grommet after all and given the pipe transfers the motion of the engine to the one way valve you sometimes can get a slight leak.
Also, on my S, I had running problem for months which I couldn't solve, eventually by sheer luck we realised the bottom of the servo had corroded and the engine was able to get additional air via the servo. The brake performance was improved by replacing it as was the engine performance, however the brake performance wasn't night and day, just a bit lighter.
Also, on my S, I had running problem for months which I couldn't solve, eventually by sheer luck we realised the bottom of the servo had corroded and the engine was able to get additional air via the servo. The brake performance was improved by replacing it as was the engine performance, however the brake performance wasn't night and day, just a bit lighter.
Johno said:
Also, on my S, I had running problem for months which I couldn't solve, eventually by sheer luck we realised the bottom of the servo had corroded and the engine was able to get additional air via the servo. The brake performance was improved by replacing it as was the engine performance, however the brake performance wasn't night and day, just a bit lighter.
had the same problem on my griff.
Hedgehopper said:
When you test the servo you should pump the pedal with the engine off to kill the vacuum. Then put your foot on the pedal, start the engine and the pedal should rise.
No the pedal should sink slightly 
another good test is after you have just switched of count how many times you can pump the pedal before the travel decreases noticeably,usually about 2/3 applications before the servo is exhausted 
Edited by Simon says on Wednesday 25th August 16:36
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